critterhunter
Posts: 2542
Joined: 9/24/2004
From: Brook Park,
OH, USA
Status: offline
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I've been playing with the charger and learning more. Despite the poor instructions this charger is great and am very happy I bought it. For the $50 price range there isn't much out there that can compete with the LCD computer settings this unit features, and it still has most or all of the other features found on more expensive chargers. I would highly recommend this charger to anybody out there.
In fact, a friend had a "dead 1700ma NICAD pack that his charger (same price range) would not charge, saying that the battery was an "open circuit". This battery had sat in a tree for about two weeks stuck in an Extreme. Anyway, I hooked it up to the Piranha, set up a program for it with the m/v at 10, and blasted 5amps into it (his charger only goes up to 4). Within twenty some minutes the battery was fully charged and only slightly warm. I also brought some eight year old AA Nicads back to life that other chargers wouldn't charge. Watching the screen, it appears the charger's computer will even drop the amp output to the battery to adjust for battery condition as it goes through the charge cycle if it needs it. Being able to keep trickle from coming on after a peak is also a plus.
Now, the more I play with this charger the more I learn (and like it). For instance, peaked a 900ma 8.4v Nimh TWICE on the HobbyZone car charger and then, right after the second peak (which only took a few minutes), I placed it on the Pirahna. Set at .9 amps (same as I had the car charger set), 900ma capacity, 3 m/v threshold...The charger ran for around 10 minutes and put roughly 100 to 200 more MA of capacity into the battery. I did this with other "peaked" batteries and had similar results. This tells me that the car chargers are false peaking and the Piranha is getting more juice into them. They were only slightly warm to the touch after the charge too, so I know it isn't cooking them.
Now, my next test will be to take a Piranha "peaked" battery at 3 m/v and put it back on at 3 m/v right away to see how many more MA it puts in. I'll then use this as a guide and right away change the m/v setting to 5 and see if it puts more MA into the peaked pack than the re-peaking at 3 m/v. I figure this should be a good test to see what the best m/v setting for a normal charge would be to get the most complete charge into a pack.
On the capacity rating setting we've been discussing...The charger will indeed finish the charge if the capacity rating is met that you set the battery for. In other words, if the charger doesn't finish it's charge by the peak threshold being triggered then it will stop once it has hit the capacity rating you specified. It acts as a safety feature to keem from cooking a battery that isn't tripping the threshold for some reason. However, many batteries (as I'm finding out) will hold a bit more MA capacity than the rating on the pack. So, my suggestion is to set capacity a few hundred or so MA higher than the pack rating. This way, if the pack can hold more capacity it won't false terminate when a lower capacity setting is reached. However, I'd only do this if I'm around the charger for the duration because if peak threshold detection fails you might blow up a pack or start a fire or something.
Another example of the poor instructions is the example of screen one while charging. The instructions say the bottom numbers are the "output voltage". You would guess that this would be the output voltage from the charger. In reality, it's the pack's voltage reading. I noticed this when the upper right amp charge number would kick down to zero for a second or two (the charger does this as part of it's charging pattern). The voltage reading will instantly start stop it's slow climb and start dropping in voltage. A second or so later when the charging amps kick back in the voltage will instantly begin to climb again. As the battery reaches it's peak you'll notice that the battery voltage slows to a stop, then begins to go backwards. I guess this is what the m/v setting is all about. A fully charged pack will begin to drop in voltage and this is how the charger (via the m/v setting) knows it's peaked. By the way, again, poor instructions....the m/v setting is PER CELL. In other words, don't add up the cells and multiply the number. The charger does that for you. If you set it at 3 m/v and install a 6 cell pack the charger knows it's really 18 m/v total.
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Piranha Digital Peak Charger Opinions (& Charging Hobby... - 
